The present invention relates to electrical power distribution switchboard cubicles and in particular, the cubicle structural members which support electrical apparatus housed within the cubicles.
Electrical power distribution and circuit protection apparatus are often housed within cubicles. A cubicle cabinet is often configured in vertically stacked sections, wherein separate apparatus are stacked one on top of the other. Each cabinet section is generally separated by a horizontal barrier, often constructed of sheet metal. Power is distributed to each apparatus in the vertical section by way of vertically aligned section busses. In many field installations, cubicle cabinet sections are aligned next to each other to make a row of cabinets. Power is distributed from one cubicle to the next by way of so-called through busses that are generally horizontally aligned and connected to the vertical bus. In this way, a row of separate cubicle cabinets has a network of vertically aligned section busses and horizontally aligned through busses which form a grid-like pattern. Electrical apparatus cubicles are sold by the Electrical Apparatus Division of Siemens Energy & Automation, Inc. as well as by other manufacturers.
Individual cubicle cabinets, such as those sold by the Electrical Apparatus Division of Siemens Energy & Automation, Inc., are often constructed with supporting frame skeletons which distribute horizontal and vertical loads. Exposed surfaces of the cubicle are often sheathed with protective side panels to inhibit entry of contaminants therein and inadvertent contact of live electrical components by maintenance personnel.
Distribution switchboard cubicles often mount and support electrical apparatus, such as insulated case circuit breakers for motor control equipment and relays, in two common configurations. One commonly employed and known configuration is the so-called fixed mount, wherein the electrical apparatus is rigidly attached to the cubicle, such as by way of nuts and bolts or other known fasteners.
Another known and commonly employed electrical apparatus mounting system within cubicles is by way of draw-out cradles. The cradle is often constructed as a generally box-like sheet metal structure with reciprocable slides built into the side walls of the cradle structure. An electrical apparatus, such as an insulated case circuit breaker, is affixed to the slidable rails, so that the apparatus can be moved in and out of the cabinet on the rails. When the electrical apparatus is inserted fully into the cubicle, a hinge-mounted door is closed to prevent inadvertent entry into the front of the cubicle.
A need exists for flexible cubicle construction which allows ready conversion by qualified service technicians from fixed-type apparatus mount to draw-out-type cradle apparatus mount in a cubicle and vice versa with a minimum of parts and labor effort.
A need also exists for cubicles which allow simultaneous use of the draw-out cradle attachment and fixed attachment apparatus in a stacked array within the same vertical cubicle section. Up to now, cubicles have only been offered with all electrical apparatus held by fixed mounts or all apparatus held within draw-out mounts. Some applications would benefit from a flexible, reconfigurable cubicle which would allow simultaneous use of fixed and draw-out apparatus mounts.
These needs for flexible, distribution switchboard system reconfigurable cubicles which allow simultaneous use of fixed and draw-out apparatus mounts with a minimum of conversion parts have been attained by the present invention.